1005123421 has 4 divisors (see below), whose sum is σ = 1005356412. Its totient is φ = 1004890432.

The previous prime is 1005123407. The next prime is 1005123461. The reversal of 1005123421 is 1243215001.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 528356196 + 476767225 = 22986^2 + 21835^2 .

It is a cyclic number.

It is not a de Polignac number, because 1005123421 - 2¹³ = 1005115229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1005123461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109900 + ... + 118693.

It is an arithmetic number, because the mean of its divisors is an integer number (251339103).

Almost surely, 2^1005123421 is an apocalyptic number.

It is an amenable number.

1005123421 is a deficient number, since it is larger than the sum of its proper divisors (232991).

1005123421 is an equidigital number, since it uses as much as digits as its factorization.

1005123421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232990.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 1005123421 is about 31703.6815054656. The cubic root of 1005123421 is about 1001.7048986687.

Adding to 1005123421 its reverse (1243215001), we get a palindrome (2248338422).

The spelling of 1005123421 in words is "one billion, five million, one hundred twenty-three thousand, four hundred twenty-one".